Recently, the usability of multimedia information has gathered attentions for handing a plurality of media information such as moving pictures, sound, and text.
A first conventional technology may be a television telephone system. The television (TV) telephone system is a system for connecting voice information through a telephone and image information through a TV bidirectionally. The TV telephone system cannot send a large amount of information since the transfer speed of the line is limited. Therefore, multimedia (MM) information in high quality cannot be exchanged. In addition, the communication information is lost on the spot, and the information generally cannot be stored and/or be reused.
A second conventional technology may be a digital video disk (DVD) system in addition to a conventional technology example for providing reusable MM information in high quality. FIG. 12 is a diagram for explaining the digital video disk system.
In the DVD system, an original image (moving image) is structured hierarchically and is compressed by an encoder. Voice is also encoded by the encoder. Synchronous signals of the image and the voice are written in an optical disk along with the respective data. A user reconstructs the encoded data stored in the optical disk by using a decoder so that high level MM information can be reconstruct, which is close to the original image and/or the original voice. The methods of encoding and decoding are standardized as MPEG-2, for example. Thus, the user can reuse the provided MM information by using a terminal apparatus including MPEG-2 decoder repeatedly whenever the user desires.
The DVD uses the optical disk as a storage medium for MM information. Therefore, a large amount of information can be distributed easily. However, a fast transmission circuit is required for handling such a large amount of information in a distribution system. Thus, a private line such as satellite broadcasting is required. In other words, when a shared distribution system is used which is generally available presently, the reusable MM information in high quality is difficult to use.
A third conventional technology may be a video letter, which is a system for transferring similar MM information as the sharable distribution system. The video letter packaged transmits compressed image/voice information by using a shared line and decodes the information in the receiver side for use. However, the video letter system is responsible for information communication in one direction from the sender side to the receiver side. Therefore, even when the incoming information can be transferred to another party directly, the information content cannot be reprocessed, which lacks convenience in using MM information.
In order to establish MM information, which can reuse MM information and can transfer it by using a shared transmission line and which is excellence in convenience for use, the data structure of transferred/stored MM information is important. The data structures in conventional technologies are as follows.
A fourth conventional technology may be an object-based MM data structure. The data structure divides MM information into small units (objects), which are hierarchically structured and is stored for being used by a user. The user uses the MM information by expanding it from the high level in the hierarchy information and obtaining a required amount of information toward the low level. For example, the object-based MM data structure includes a background, a foreground human character, a desk and a chair in computer graphics.
A fifth conventional technology has been proposed for constructing MM information by content information and behavior information and transferring the MM information as package information including them according to Multimedia and Hypermedia information coding Expert Group (MHEG). The MHEG data structure can conveniently provide a function for reconstructing received data automatically in the receiver side by writing an automatically reconstructing function in the behavior information.